Strange L-48 stumbling
Thread Starter
Burning Brakes
Joined: Jul 2014
Posts: 831
Likes: 54
From: Arlington TX
Strange L-48 stumbling
Hello all!
I have a strange issue. And I can't seem to find anyone else that has had the same issue. Two separate rpm specific issues.
First, From a dead stop wot it climbs steady till hitting 2300 rpms then struggles dramatically to pull to reach 2500 rpms. Acceleration drops significantly here.
Second... Moving on through the rpm range at around 2900 it stumbles heavily once then continues to climb up the rpms.
The power band is so spotty feeling throughout the rpm range.
Any ideas? Motor and trans where rebuilt right before it was out up 15 years ago. Likely has less than 5k miles in em.
Any ideas where or how to start trouble shooting components?
Thanks!
I have a strange issue. And I can't seem to find anyone else that has had the same issue. Two separate rpm specific issues.
First, From a dead stop wot it climbs steady till hitting 2300 rpms then struggles dramatically to pull to reach 2500 rpms. Acceleration drops significantly here.
Second... Moving on through the rpm range at around 2900 it stumbles heavily once then continues to climb up the rpms.
The power band is so spotty feeling throughout the rpm range.
Any ideas? Motor and trans where rebuilt right before it was out up 15 years ago. Likely has less than 5k miles in em.
Any ideas where or how to start trouble shooting components?
Thanks!
Race Director
Joined: Sep 2001
Posts: 10,560
Likes: 441
From: Wellington, FL
St. Jude Donor '11 thru '25
When was the last tune up? Fouled/old plugs and/or bad wires can raise some hell but are not so noticeable at low RPM's.
Last edited by Jud Chapin; Feb 20, 2015 at 07:08 AM.
Burning Brakes
Joined: Oct 2008
Posts: 1,037
Likes: 15
From: Mobile Alabama
Of course, I would check the ignition and tuning, but you could have exhaust restriction from converter or pipe/mufflers. There is also fuel restriction from plugged filter/s or tank sock, or pressure/volume from fuel pump. My first check would be replacing the fuel filter and a tuneup.
Thread Starter
Burning Brakes
Joined: Jul 2014
Posts: 831
Likes: 54
From: Arlington TX
Thanks for the replies. New plugs went in a few months back. The wires seem to be in tip top. I can't imagine exhaust restriction causing that exact rpm stumble but then again, I have headers and new mufflers that will be going on in a few weeks anyhow, so we will see.
Since the issue is so precise and consistent, I'm thinking the distributor is the culprit. But that thing looks like it's brand new on the inside. Definitely not the original build.
Since the issue is so precise and consistent, I'm thinking the distributor is the culprit. But that thing looks like it's brand new on the inside. Definitely not the original build.
Race Director
Joined: Sep 2001
Posts: 10,560
Likes: 441
From: Wellington, FL
St. Jude Donor '11 thru '25
Thanks for the replies. New plugs went in a few months back. The wires seem to be in tip top. I can't imagine exhaust restriction causing that exact rpm stumble but then again, I have headers and new mufflers that will be going on in a few weeks anyhow, so we will see.
Since the issue is so precise and consistent, I'm thinking the distributor is the culprit. But that thing looks like it's brand new on the inside. Definitely not the original build.
Since the issue is so precise and consistent, I'm thinking the distributor is the culprit. But that thing looks like it's brand new on the inside. Definitely not the original build.
Thread Starter
Burning Brakes
Joined: Jul 2014
Posts: 831
Likes: 54
From: Arlington TX
Race Director
Joined: Sep 2001
Posts: 10,560
Likes: 441
From: Wellington, FL
St. Jude Donor '11 thru '25
BTW, don't forget the cap, rotor and filters including the one in the carb. I would also check fuel pressure. Check it at idle and then by reving the engine to verify both readings are within spec. And how old is the gas?
Good luck. Stay with and you'll find the answer.
Burning Brakes
Joined: Oct 2008
Posts: 1,037
Likes: 15
From: Mobile Alabama
The miss is there at lower RPM's with bad plugs or wires, you just don't feel it as much. Ask me how I know. Bottom line on this problem is that you have to keep eliminating possibilities until you find the cause. (Do the easiest things first.) At this point, you don't know whether it's gas on electrical in nature. Also keep in mind that no one on this forum or anywhere else knows the answer w/o doing actual troubleshooting on the car.
BTW, don't forget the cap, rotor and filters including the one in the carb. I would also check fuel pressure. Check it at idle and then by reving the engine to verify both readings are within spec. And how old is the gas?
Good luck. Stay with and you'll find the answer.
BTW, don't forget the cap, rotor and filters including the one in the carb. I would also check fuel pressure. Check it at idle and then by reving the engine to verify both readings are within spec. And how old is the gas?
Good luck. Stay with and you'll find the answer.
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